Experimental and simulation study of preformed particle gel-assisted conformance control in dual sandpack systems for enhanced oil recovery

Controlling water channeling in heterogeneous reservoirs remains a major challenge, and preformed particle gels (PPGs) have been increasingly investigated and applied as conformance control agents to improve sweep efficiency under specific reservoir conditions. However, existing studies have largely examined individual controlling factors in isolation, and the coupled influence of geological heterogeneity, brine salinity, and nanocomposite gel formulation on PPG transport behavior and recovery performance has not been systematically quantified. This study presents an integrated experimental–simulation assessment to address these mechanisms. Dual parallel sandpack experiments were performed to evaluate oil recovery, plugging efficiency, and flow redistribution under varying permeability contrasts, salinity levels, and gel types. In parallel, a coupled MATLAB–Eclipse simulation framework was developed, in which key permeability- and wettability-related parameters were optimized using a genetic algorithm. The primary contribution of this work is evaluating the recovery behavior of a newly formulated nanocomposite PPG whose performance under realistic displacement conditions has not been previously reported. In addition, this study quantitatively elucidates how the coupled effects of permeability contrast, brine salinity, and nanocomposite PPG properties govern flow diversion efficiency and recovery enhancement, based on combined dual-sandpack experiments and mechanistic simulation. The optimized simulations successfully reproduced experimental trends and confirmed that permeability reduction and wettability alteration are the dominant mechanisms governing recovery enhancement during low-salinity PPG treatment. Lak wettability index analysis revealed a consistent trend toward more water-wet conditions after treatment, corroborating the relative permeability and recovery results. The results show that nanocomposite PPGs combined with low-salinity NaCl brine (4000 ppm) provide superior swelling behavior, plugging strength, and permeability reduction. Moreover, a moderate permeability contrast (8:1.5) was found to yield the most effective flow diversion. Overall, the proposed integrated framework offers a predictive basis for designing improved PPG-based conformance control strategies in heterogeneous reservoirs.